Tagetolone and tagetenolone: two phytotoxic polyketides from Alternaria tagetica

Two new phytotoxic polyketides, tagetolone (1) and tagetenolone (2), in addition to tyrosol and p-hydroxybenzoic acid, have been isolated from the organic crude extract of culture filtrates from the fungal pathogen Alternaria tagetica. Complete characterization of all structures was carried out following a careful analysis of their spectroscopic data (IR, MS, (1)H and (13)C NMR, and 2D NMR experiments).     

Effect of processing on the antioxidant vitamins and antioxidant capacity of Vigna sinensis Var. Carilla

Cowpea (Vigna sinensis L. var. Carilla) flours obtained by fermentation with inoculum Lactobacillus plantarum (PF) or with the natural microorganisms present in the flour (NF) and subsequent heat treatment in an autoclave were prepared to study the effect of fermentation on the antioxidant vitamin content and on the antioxidant capacity. Bacterial counts and pH values, vitamins C and E, carotenoids, glutathione (GSH), superoxide dismutase-like activity (SOD-like activity), peroxyl radical-trapping capacity (PRTC), lipid peroxidation in unilamillar liposomes, and Trolox equivalent antioxidant capacity (TEAC) were evaluated in raw and processed cowpea flours. gamma-Tocopherol and delta-tocopherol were found in raw cowpea, whereas vitamin C and carotenoids were not detected. An increase in the vitamin E activity was observed in PF, whereas vitamin C and carotenoids were not detected in fermented cowpea flours. Fermentation or heat treatment in an autoclave after fermentation produced processed cowpea flours with lower PRTC, glutathione content, and SOD-like activity than those of the raw seeds. However, those processes increased the capacity to inhibit the lipid peroxidation in unilamellar lipoposomes and TEAC. According to the results obtained in this study, the fermentation of cowpeas (naturally or with L. plantarum) and fermentation and subsequent heat treatment in an autoclave are good processes to obtain functional cowpea flours having higher antioxidant capacity than the raw legume.     

Simultaneous and sensitive detection of three foodborne pathogens by multiplex PCR, capillary gel electrophoresis, and laser-induced fluorescence

The simultaneous detection of Staphylococcus aureus, Listeria monocytogenes, and Salmonella spp. has been approached by a new multiplex PCR-based procedure followed by capillary gel electrophoresis with laser-induced fluorescence detection (multiplex-PCR-CGE-LIF). As compared to slab gel electrophoresis, the use of CGE-LIF improved from 10- to 1000-fold the sensitivity of the multiplex PCR analysis, allowing the detection of 2.6 x 10(3) cfu mL(-1) of S. aureus, 570 cfu mL(-1) of L. monocytogenes, and 790 cfu mL(-1) of Salmonella in artificially inoculated food, without enrichment. Following 6 h of enrichment, as low as 260, 79, and 57 cfu mL(-1) of S. aureus, L. monocytogenes, and Salmonella, respectively, were detected. The CGE-LIF method is shown to be reproducible, providing relative standard deviation (RSD) values lower than 0.8% for analysis time and lower than 5.8% for peak areas. The multiplex-PCR-CGE-LIF proved a powerful analytical tool to detect various food pathogens simultaneously in a fast, reproducible, and sensitive way.     

Vitamin C,provitamin A carotenoids,and other carotenoids in high-pressurized orange juice during refrigerated storage

Vitamin C, provitamin A carotenoids, and other carotenoids were measured in freshly squeezed juices from oranges (Citrus sinensis L. var. Valencia late) that were subjected to high-pressure (HP) treatment. Also, the stability of these compounds was studied during refrigerated storage at 4 degrees C. HP treatment is an alternative to heat preservation methods for foods; therefore, it is essential to assess the impact of HP on bioactive compounds. Several processes that combine HP treatment with heat treatment for various time periods were assayed: T0, fresh juice (without treatment); T1, 100 MPa/60 degrees C/5 min; T2, 350 MPa/30 degrees C/2.5 min; T3, 400 MPa/40 degrees C/1 min. Fresh and treated samples were kept refrigerated (4 degrees C) over 10 days. After application of HP and during the refrigeration period, the qualitative and quantitative determination of vitamin C, provitamin A carotenoids (beta- and alpha-carotene; beta- and alpha-cryptoxanthin), and the xanthophylls zeaxanthin and lutein was achieved by high-performance liquid chromatography. T1 and T3 juices showed a decrease in ascorbic acid and total vitamin C just after HP treatment (D0) compared with T0 juices. On the contrary, T2 juices, just after HP treatment (D0), had the same levels of both compounds compared to untreated juices. T1, T2, and T3 treatments led to an increase in the extraction of carotenoids and provitamin A carotenoids. Total carotenoid content after the 10-day refrigerated storage period resulted in no significant quantitative changes in T1 juices, whereas in T2 and T3 juices small losses were found at the end of the storage period (20.56 and 9.16%, respectively). These losses could be influenced by the depleted protection of vitamin C toward carotenoid oxidation during the same period. A similar trend was found in provitamin A carotenoids for the different treated juices.     

Volatile compounds in Hispánico cheese manufactured using a mesophilic starter,a thermophilic starter,and bacteriocin-producing Lactococcus lactis subsp. lactis INIA 415

The effect of the addition of Lactococcus lactis subsp. lactis INIA 415, a strain harboring the structural genes of nisin Z and lacticin 481, on the formation of volatile compounds in Hispánico cheese manufactured with a mesophilic starter or with the mesophilic starter and a thermophilic starter was investigated. Addition of bacteriocin-producing L. lactis subsp. lactis INIA 415 to milk enhanced the formation of 2-methyl-propanal, 2-methylbutanal, 3-methylbutanal, 2-methyl-1-propanol, 3-methyl-1-butanol, 1-octanol, 2-butanone, and 2,3-butanedione. On the other hand, addition of thermophilic starter enhanced the formation of acetaldehyde, ethanol, 3-methyl-2-buten-1-ol, ethyl butanoate, ethyl hexanoate, 2-butanone, and 2,3-butanedione in Hispánico cheese. Stepwise discriminant analysis using the relative abundances of volatile compounds classified cheeses by type of starter, with function 1 related to thermophilic starter and function 2 to bacteriocin producer.     

Effect of pH and ionic strength modifications on thermal denaturation of the 11S globulin of sunflower (Helianthus annuus)

Helianthinin, the main storage protein of sunflowers, has low water solubility and does not form a gel when heated; this behavior is different from other 11S globulins and limits its food applications. To understand this particular behavior, changes on helianthinin association-dissociation state induced by modifications in pH and ionic strength were analyzed. The influence of these different medium conditions on its thermal stability and tendency to form aggregates was also studied. Helianthinin behavior at different pH values and ionic strengths is similar to other 11S globulins except that it remains in a trimeric form at pH 11. Helianthinin thermal stability is higher than other 11S globulins but is lower than oat 11S globulin. Alkaline pH produces a 10 degrees C decrease of its denaturation temperature and also of the cooperativity of denaturation process, but it does not affect the denaturation activation energy. The decrease in thermal stability with the pH increase is also manifested by its tendency to form aggregates by SH/SS interchange reactions. When thermal treatments at alkaline pH are performed, all helianthinin subunits form aggregates, characterized by a higher proportion of beta-polypeptides than alpha-polypeptides, which is an indication that aggregation is accompanied by dissociation. Treatments at 80 degrees C are sufficient to induce aggregation but not to produce denaturation, and in these conditions hexameric forms remain after the treatment.     

Do pine plantations provide mycorrhizal inocula for seedlings establishment in grasslands from Patagonia,Argentina?

We investigated if Pinus ponderosa plantations in Patagonia are able to produce viable mycorrhizal inocula towards adjacent grasslands, which only harbor endomycorrhizal vegetation. We hypothesized that these inocula have the potential to contribute to the establishment of naturally disseminated seedlings. Also, we determined the main fungal taxa involved in this process. Seven plantations in the onset of their reproductive phase and located in the Patagonian native forest/steppe ecotone (Argentina) were selected. Soil samplings were obtained at nine points along a 450 m long, W-E transect established in each plantation. Soil bioassays were performed in a greenhouse, with P. ponderosa seedlings acting as hosts for mycorrhizal inocula present in soil samples, during 12 months. Mycorrhization percentage, morphotype richness and morphotype composition was determined through morphological evaluation. Viable ecto- and ectendomycorrhizal inocula were found disseminated outside plantations. The amount of mycorrhizal inoculum followed a decreasing function with distance to plantation edges. Mycorrhizal fungal genus Rhizopogon and “E-strain” mycorrhizal types appeared as pioneering taxa regarding seedlings colonization, being the most persistent and frequent symbionts found. Plantations, thus, facilitate the surrounding terrain for newcoming seedlings through the dispersion of mycorrhizal fungal inocula.     

DRIS norms and limiting nutrients in banana cultivation in the South of Ecuador

Abstract

Foliar analysis is an effective method to diagnose the nutritional status of plants. However, the mineral concentration in foliar tissue has traditionally been evaluated by assessing the activity of each element, without considering the interactions between them. To address this, dual interactions were calculated using the Diagnosis and Recommendation Integrated System (DRIS) to identify which crop nutrients are most influential in nutrient imbalances and which are the most limiting nutrients for the nutritional status of banana crops in Ecuador. To achieve this, a regional survey of the nutritional status and its productivity levels was conducted for 188 different sites during the crop season in 2017–2018, involving banana cultivars ‘Vallery’ and ‘Williams’, from the Cavendish subgroup. The DRIS calculation method was combined with Beaufils and Jones functions. From the initial 188 foliar samples, 83 samples (representing 44% of the population) were considered to represent the high-yield reference population, with yields of 38–60 t ha^?1. The DRIS method defined the mean nutritional balance index, which was not found to be statistically correlated (p?>?0.05) with productivity, revealing that there was no significant association with the nutritional status of the plants. Specific DRIS norms were obtained and indicated that deficiencies in K, N, Ca, and Fe, and excesses in Mn, B, Cl, Zn, S, Cu, and Mg were the most limiting nutrients for banana cultivars in the south of Ecuador.     

Diterpenes from Salvia broussonetii transformed roots and their insecticidal activity

The new diterpenes brussonol (1) and iguestol (6alpha,11-dihydroxy-12-methoxy-abieta-8,11,13-triene) (2) with an icetexane and a dehydroabietane skeleton, respectively, have been isolated from hairy root cultures of Salvia broussonetii. Other previously known diterpenes, 7-oxodehydroabietane, 11-hydroxy-12-methoxyabietatriene, taxodione, inuroyleanol, ferruginol, deoxocarnosol 12-methyl ether, cryptojaponol, pisiferal, sugiol, isomanool, 14-deoxycoleon U, 6alpha-hydroxydemethylcryptojaponol, demethylsalvicanol, and demethylcryptojaponol, were also obtained from these roots. The insect antifeedant and toxic effects of several of these compounds were investigated against the insect pests Spodoptera littoralis and Leptinotarsa decemlineata. Additionally, their comparative cytotoxic effects were tested on insect Sf9 and mammalian CHO cells. Demethylsalvicanol (4) was a moderate antifeedant to L. decemlineata, whereas brussonol (1) was inactive. 14-Deoxycoleon U (15) was the strongest antifeedant, whereas demethylcryptojaponol (11) was toxic to this insect. None of these compounds had antifeedant or negative effects on S. littoralis ingestion or weight gains after oral administration. Demethylcryptojaponol (11) was cytotoxic to mammalian CHO and insect Sf9 cell lines, followed by the icetexane derivative brussonol (1), with moderate cytotoxicity in both cases. The remainder of the test compounds showed a strong selective cytotoxicty to insect Sf9 cells, with demethylsalvicanol (4) being the most active.